Try Air Canada...
Not sure how "close" to 7k you need, but LHR - YUL (Montreal) gives you just under 7k for:
AC865 London (LHR) Montreal (YUL) Thu 03-Feb 14:05 16:30 0 7hr25 333 Economy (lowest price)
AC864 Montreal (YUL) London (LHR) Thu 10-Feb 19:55 07:30
+1 day 0 6hr35 333 Economy (lowest price)
Airfare (Economy (lowest price)) 217.00
Canada Airport Improvement Fee 6.30
U.K. Passenger Service Charge 10.40
Canada Quebec Sales Tax (QST #1000-043-172) 0.50
Canada Goods and Services Tax (GST/HST #10009-2287) 0.40
U.K. Air Passenger Duty 20.00
Canada Security Charge 8.40
Carrier Admin. Service Charge 16.00
Grand Total - Pound Sterling Convert currency £ 279.00
All Air Canada Long-Haul eco. fares are full earning (1.0x). Economy's not that bad, either, and you could maybe combine it with a weekend skiing in Tremblant or something.
If you need a <bit> further in terms of miles, try Toronto for £228.50 all-in. (but obviously a slightly longer flight, if you're concerned with time.)
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OR, if you're already a *G/*S, you can get an auto-"upgrade" to United's Economy Plus (37" I think) on a New York or Boston trip, AND you'll get double destinations miles until mid-Feb (17th, I think?), too:
1:20pm Depart - London Heathrow, UK (LHR) United Airlines 905
4:10pm Arrive - New York-Kennedy, NY (JFK) Nonstop
Total Travel Time: 7 hrs 50 min
7:00pm Depart - New York-Kennedy, NY (JFK) United Airlines 9566:55am Arrive - London Heathrow, UK (LHR) Nonstop
Total Travel Time: 6 hrs 55 min
1 adult = GBP 143.00
Taxes and Fees = GBP 56.70
Service Fee = GBP 6.00
Total Price = GBP 205.70
I know it's transatlantic, but it'll work out a lot less than 2x Euro-Biz tickets, and has potentially more fun involved....!